Comparing the time course of life and stars

I do like being surprised when big chunks of time are put into context. I had that with Into Eternity on the 100,000 thousand year notion of “big”, and I’ve had that feeling again on the 500+ million year notion of “big”.

I’ve quoted Otherlands before, and I’m going to do it once more. This time, the context is life on earth and the age of stars. The Ediacaran period was when complex life started to appear:

The Ediacaran is more than two galactic years in the past—that is, the solar system has circled the black hole at the centre of our galaxy more than twice in the intervening time, a total voyage of over 350,000 light-years. Our nearest stellar neighbours are on different trajectories, and we have left them all behind. Even if we had not, many of the stars we are familiar with are yet to be born. We may be in the northern hemisphere, but you won’t find Polaris, which first shone out in our Cretaceous. None of the seven stars that make up Orion’s distinctive shoulders, feet and belt, is older than the Miocene. Sirius, the brightest night-star of the modern day, has a long history, but even its Triassic birth is further into the Ediacaran future than the Holocene past.

I checked, and Polaris the star is 50 to 60 million years old. I’d never put together the age of stars with the huge time span that life has been evolving.